Circuit breaker



BEST AVAILABLE COP p 1941- I A. J. THOMSON Re. 21,760

cmcurr BREAKER I Origina'l Fild March 6, 1933 2 Sheets-Sheet 1 INVENTOR.

BY 6W BEST AVAILABLE COP;

April 1, 1941. J; THOMSON 7 Re. 21,760

I CIRCUIT BREAKER Original Fiied March 6, 1933 2 Sheets-Shae 2 Reis'sued Apr. 1, 1941 BEST AVAILABLE c op.

UNITED 'STATEVS PATENT oi-"P ca Alfred J. Thomson, Detroit,

Bulldog Electrlo mehsll l rto Detroit,

Products company M leh..acorporatlonofWeet virgins Original No. 2,102,295, dated December 14, 1937,

Serial No. 659,714, Hatch 6, 1938.

. 1. mm This invention relates to operating mechanisms for circuit breakers.

Herein disclosed is a novel operating mechanism, the provision of which isa principal object of the invention.

Among the characteristics of the mechanism disclosed in the drawings. are the following:

Renewed tlon for reissue annary Mi September 9, 1940, 801131 No. 356,071

(01. zooila) (1) Themechaninnistripfrec:thatistosay.--

upon release of the mechanism parts by the overload release element, the mechanism parts will 10 trip and move to their overload released position.-

even though the handle, which normally operates the mechanism, is held against movement intentionally or accidentally; the mechanism parts trip for overload release. free of the handle.

(2) The mechanism is so constructed is to' have quick action on normal operation, and on overload release, and these actions are accomplished even though a relatively small number of parts are used in the mechanism.

(3) The connection between the operating handle andthe m parts, though permih ting quick action, is positive, that'even though i the springs which provide the quick action should become injured, or prove insuilicient to cause action, or so thateven tholllh the sticks, action can be accomplished positively by movement of the handle.

(4) The operating springs arein nature of I compression springs, which is of advantage, due

to the fact that-compression springs are-more satisfactory of operation-than otherforms 01 springs (5) l 'urther. the compression springs. are

mounted on links so that in the event a spring breaks, the broken parts will not'fall into and among live parts, with consequent damage. v

(6) Further, the operating compressionsprings are so podtioned and connectedthat they need be flexed only a relatively small distance, as contreated with other wherein considerable flexing of the springs is required, it being observed that l'of the-required eilect of prolonging the mns i s has h llfeofthesprings.

('7) Further. the Sprin s are, not connected to the operating handles, and therefore, the handles can be moved, for poutive action, independentLv of the springs. r r

(8) I'm-then reset action. after overload "03;"

" tripping. can be ed' without the 0m! of the mechanismmoving out of "off" r armorlink stillfurtherobjectswiilreadiiyoccurtothoee skilled in'the art upon reference'to the follow- (shaft 0) tion (Figure 2).

-to the right, the hell crank I. rotates clockwise,

ing description and the accompanying drawings in which- Figs. 1-3 are plain, elevation, and end views, respectively of an ,operatingmechanism for a circuit breaker, shown in "on" position;

Figs. 4 and 5 show the device in o position and overload "o position, respectively.

The device of Figures L-S In Figures 1 to 5 there is shown a circuit breaker operating mechanism having three positions, "on" (Fig. 2), switch oiP (Fig. 4) and overload "01!" (Fig. 5).

The device includes a base lil. To the line is connected one leg ot the thermostatic or bimetallic warping element It, the other leg of the latter being connected to the load. When the m is in on@ position, current flows through warping element It.

A coiled compression resisting spring 21 is 'mounted on the right hand end of link 24, be-

tween a 28' thereon and the bight of a U- shaped, horizontally positioned spring compression link a, whichls pivotally connected at an to a pawl 82,:the latter being pivotally connected by shouldered screws "on its left hand end to 'frontplate 2i and vertical back plate 1434. As indicated. thelink it passes through a slot in the. bight of link 29, and these links move as a unit, around pivot 3|. 1n the on" position, the right handlor free end II of pawl 32 is held down by'a' tongue ll of warping element II.

The left hand end 31 of link 24 is pivotally connected to an operating bell crank it by a pin 39,

thelatter sliding in an arcuate slot ll of the crank. The bell crank has an extension 42 forming an operating handle for the device, and is pivotally supported on the cross shaft II, the latter connecting front plate fl and the vertical backpl teflo.

The parts .iustdescribed may be operated asv follows: Assume the parts to he in "on posi- When the handle I! is moved carrying end 8! of link 24 along with it, thus moving links I and ll, together, about the pivot II. clockwise. This action pulls link 24 to the left a-slight degree and builds up an increased compression in springs 11.

2 4 has passed over center coil spring. operates, to move links further shaft ll. with a snap acsnap action movement of 26 and M l permitting 2 tlon, slot =55 llnks a and an. independently of the handle 4:,

vided in slot 4i.

BEST AVAILABLE COP",

so that quick action may be effected indepe ently of the operator.

treme 011" position as limited by the engagement of the reset lug 44 and stop 4| on pawl 22. Reverse movement of handle 42, to the left,

" from the "off" position (Fig. 4) imparts a counter-clockwise movement to link 24 about pin II. This action pulls link 24 to the left and compresses spring 21 between pin 2| and the bight past center (shaft 42) Then the compressive force of the spring reacts, giving a rapid counter-clockwise movement to link :4.

'mined by the length of slot 4i, and the "on position of link 24, as shown in Fig. 2.

The action just described is a quick action, and

position,

drum II to rotate clockwise, to pull the left end [of link 24 clockwise, and upwardly to the posiof the spring compression link 20. until link 24 is takes place when spring 21 functions properly.

At other times, the handle. and link insures action.

Duringthe operation, travel-of pawl 22; about its pivot screws .22 is prevented, by its end ll being held by the tongue 24 of warping element l4.

It will be observed that slot 4| provides a lost motion connection between, handle 42 and link 24, which permits movement of the latter, when overcenter and as influenced by spring 21, independently of the handle for accelerating the quick action of the link 24, the extent of this action being determined by the dimensions of slot 4| and the associated parts. A positivemake and break action of the linkage is, however, assured by the positive (even though lost motion) positive connection between 24, as previously described.

. connection between handle 42' and link 24.

The foregoing parts, in conjunction with other parts to be described below, move from "on" position to a second or overload "0! position, when element I4 warps to the right due to an overload in the line, and also serves to enable the operator to reset the mechanism after it had been tripped on overload, by moving the various parts, linkages, and the pawl 02 from their overload "0 position to their normal "0 causing link 24 to assume the position of Fig. 2, and these operations are carried on as follows:

Assume the switch to When the element l4 warps (to the right) its tongue ll releases pawl end ll. permitting the compression in spring 21 to tend to move link 2|, and consequently pin ii. to the left. Since link 29 is fixed to pawl'l2 at 2|, the movement of pin position without be in "on" position.

2| to the'left is on an arc whose'center is pivot" 22, and is necessarily accompanied by an upward say, to be moved from tion shown in Figure 5, known as "overload ofl'." Quickaction is of course assured by the action of spring 21.

In view of the fact that this action can take" place without interference from handle 42, due

to the fact that the pivot 20 need not move anygreat extent on this action, the mechanism cannot be prevented from tripping, merely by hold.- ing handle 42. In other words,-the mechanism will trip even though the handle be held. This characteristic places the mechanism in the tripfree class.

When the parts are to be reset, that is to to switch the right, rotating bell crank 48 clockwise until the lower edge of elongated slot 4| comes in contact with pin 22 carrying it past center (shaft 42). The spring 21 then continues the clockwise movement of pin 22 pivoting link 24 about pin 2i until shoulder 42 on spring compression link 22 engages shoulder II on link 24. v Y 3 A continued movement of the handle to the right causes the stop lug 44 on bell crank 28 to engage stop 4! on pawl 22, rotating the latter clockwise aboutscrews 22 until its end II snaps under to gue I! of warping element l4, resetting the parts to the "off". position of Figure 4.

By properly proportioning and connecting the parts, the action may be such that during move: 42, lug 44 can be resetting ment of the handle link 22 to its normal latched position, during the time that link 24 is moving overcenter to the "ofl" position.

' It will be observed at this time that the'mcchanism described in the foregoing possesses certain novel and desirable characteristics. It is trip-free; it operates with a quick action, both on normal switch operations, and on overload; it insures positive action, in addition to and without interfering with the quick action; and it can be reset after tripping, with a snap action.

In addition, in the event the spring 21 breaks, it will not fall into live parts with'consequent damage, but will remain upon the link 24 upon which it is mounted, being held between pin 2| and link 29.

Further, since the spring 21 does not have to the hannot interfere with positive action of the handle, as contra-distinguished from constructions wherein the spring connects the operating linkv or part to the reference will be had to the following claims which determine thescope of the invention, it being expressly understood that the mechanism heretofore described and disclosed has been chosen merely as an example,

trating all of the posible embodiments of the invention.

I claim: 1. A circuit breaker eluding an e ongated overload of!" (Fig. 5) "oil'" (Fig. 4), handle 42 is moved to e per- 4 handle.

Now having described one form ofmechanism,

operating mechanism pawlflxedlypivotedatime BEST AVAILABLE COP end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost-motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and .to the pawl.

2. A circuit breaker operating mechanism including qn'elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed pant and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected, at one end to said crank by a positive, lost motion 'pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to :the pawl, the spring providing a. quick movement for the operating link.

3. A circuit breaker operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held-down at the otherend by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for 618 -8 8 said pawl and resetting it by moving it downwardly al'ter it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent thepivotal connection of the pawl, a com pression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the aforesaid links moving about themonnection between the spring compression link and the pawl, as a pivot, with the pawl at rest, during manual operation.

4. A circuit breaker operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted toa fixed part and having a reset part for engaging said pawland resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl,

with its aforesaid pivotal connection adjacent the pivotalconnections 01' the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the link moving about the connection between the spring compression link and the pawl, as a pivot, with the pawl at rest, during manual operation, the spring providing a quick movement for the operating link.

5. A circuit breaker operating mechanism in-qg eluding an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end 01' said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the operating link and .the pawl together moving about their adjacent pivotal connections as pivots, on overload release movement.

6. A circuit breaker operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection oi the pawl, a compression spring on the end oi said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the operating link and the pawl together moving about their adjacent pivotal connections as pivots on overload release movement, the spring providing a quick movement for the operating link.

7. A circuit breaker operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an op-. crating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside saidpawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end 01' said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to 'the pawl, the links moving about the connection between the spring compression link and the pawl, as a pivot, with the pawl at rest, during manual operation, the operating link and the pawl together moving about their adjacent pivotal connections as pivots, on overload release movement.

8. For use with a'contact to which it may be operatively connected so as to form a circuit breaker controlling mechanism, a resilient mechanism, a

movable current responsive latch so constructed and arranged that it normally engages the mechanism for holding it, the parts being so arranged relatively that the mechanism, when held by the latch, is under longitudinal stress, the latch being movable on a circuit abnormality for releasing the mechanism, a rotatably mounted handle, means operatively connecting it to the mechanism, the handle being so constructed and arranged that'on rotary movement thereof out of its BEST AVAILABLECOP. j

normal position it will" stressthe mechanism longitudinally and move it bodily out of its normal position and towards the center of rotation otthe handle so that when the handle is released after such movement the mechanism will tend to relieve itself or the'longitudinal stress created therein by such movement or the handle with a snap action, the parts being so arranged relatively that on such stress relieving movement or the mechanism following such handle movement and subsequent release. the mechanism will move bodily beyond the center of rotation of the handle and about the connection between the mechanism and latch as a pivot, and also being so arranged relatively that on release of the latch, when the. handle and mechanism are in normal position, the mechanism will tend to relieve itself of the stress that it possesses when it is held by the latch with a snap action and in so doing will move bodily about it: connection to the handle as a pivot.

9. A construction 01' the character described 1: claim 8, wherein the handle is so arranged relatively to the mechanism that it may be manipulated to reset the mechanism into normal position and held by the latch under stress, following movement thereof responsive to release of the latch, by movement or the'handle in a manner generally similar to the movement thereof that causes movement or the mechanism out of normal latch held position.

10. A construction of the character described in claim 8 wherein the points of connection between the handle and mechanism and between the latch and mechanism are spaced from each other.

AIFRED J. THOMSON. 

